s=input()
s1=''
for a in s:
    if (a=='(' or a=='{' or a=='<' or a=='[') or s1==' ':
        s1+=a
    elif s1!='':
        if (a==')' and s1[-1]=='(') or (a=='}' and s1[-1]=='{') or (a==']' and s1[-1]=='[') or (a=='>' and s1[-1]=='<') :
            s1=s1[:-1]
if s1=='':
    print('верная')
else:
    print('неверная')
